1. Field of the Invention
The present invention relates to a digital broadcast receiver, and more particularly to a downloading apparatus and a method thereof for a digital broadcast receiver, capable of downloading programs of a microcomputer.
2. Discussion of the Background
Currently, most digital broadcast systems obey a MPEG standard, and a MPEGII system for broadcasts is divided into sections of a system, a video and an audio standard.
Among them, the system standard is to prescribe a time-multiplexed signal stream called a transport stream packet. There is a header at a start section of the transport stream packet, and packet identifier (PID) numbers indicating header. The PID numbers which provide essential information for inverse multiplexing of time-multiplexed signal streams are identifying numbers indicating whether a current packet is a video, an audio or an additional information packet.
The video and audio standards for visual and audio signal streams which are respectively compressed by the MPEGII system. These signal streams are divided by the PIN numbers, and video, audio and additional information become time-multiplexed and transmitted through several transport stream packets.
FIG. 1 is a block diagram of a general digital broadcast receiver for a TV.
As shown therein, the general digital broadcast receiver is provided with: a link unit 100 for detecting and correcting a quadrature phase shift keying (QPSK) signal or a quadrature and amplitude modulation (QAM) signal, which is inputted through an antenna ANT, for thereby outputting a transport signal stream; a system decoder 110 for performing inverse-multiplexing of the transport signal stream from the link unit 100, that is for dividing the transport signal stream from the link unit 100 into video, audio and additional information signal streams; a video decoder 120 for expanding the video signal stream divided by the system decoder 110; an audio decoder 140 for expanding the audio signal stream divided by the system decoder 110; an encoder 130 for converting the video signal from the video decoder 120 to a luminance signal Y and a chrominance signal C to be displayed on a TV or a monitor; a D/A converter 150 for converting the digital audio signal from the audio decoder 140 to an analog audio signal; a microcomputer 160 for controlling functions of the additional information signal stream separated by the system decoder 110 or additional information supplied from a user interface 190; a ROM 170 for storing a main program for driving the microcomputer 160; a RAM 180 for temporarily storing variables for an operation of the microcomputer 160; and a data bus and an address bus for receiving and transmitting data and address in each unit.
FIG. 2 illustrating a map of the ROM 170 in FIG. 1. As shown therein when power is applied to the ROM 170, the main program is instantly processed.
Now, an operation of the general digital broadcast receiver will be describe with reference to the accompanying drawings.
The link unit 100 detects and corrects the QPSK or QAM signal from the antenna ANT and outputs a resultant transport signal stream to the system decoder 110.
The system decoder 110 which receives the transport signal stream detects the PID numbers, that is inverse-multiplexing, for thus dividing into the video, audio and additional signal streams, and applies the video signal stream to the video decoder 120, the audio signal stream to the audio decoder 140 and the additional information stream to the microcomputer 160, respectively.
The video decoder 120 expands the video signal stream which is compressed by the MPEGII, and the encoder 130 converts the video signal from the video decoder 120 to the luminance signal Y and the chrominance signal C to be displayed on the TV or the monitor.
While, the audio decoder 140 expands the audio signal stream which is also compressed by the MPEGII, and the D/A converter 150 converts the digital audio signal supplied from the audio decoder 140 to an analog audio signal.
The microcomputer 160 performs a control operation in accordance with the main program stored in the ROM 170 in order to carry out a function which corresponds to the additional information signal from the user interface 190 such as a remote control, a function key, etc. Here, the variables which are required for the operation of the main program are reserved in the RAM 180 and used whenever necessary.
However, when changing the main program stored in the microcomputer 160 in the digital broadcast receiver of the TV, for example, in a case of updating the program to receive any additional function or service, or changing the program due to discovery of bug therein, it is required to change the whole ROM in the digital broadcast receiver, which is troublesome to the TV user.